This invention relates to an image processing apparatus for editing, filing, and printing out image data such as document information stored in a bit map memory, by means of visual observation of the document image on a display screen.
Nowadays, there are many types of data processors which can perform image data processing. These include personal computers, work stations, electronic filing systems, and image editing systems. The main demands of the major users in this field are for an increase in the data processing speed, and for the attainment of a parallel processing capability.
An image data processing apparatus needs to perform a number of functions. For example, one function needed is to input character data to the image processor or the message is displayed on the screen while the image data is stored in the bit map memory, by using an image input/output device such as a scanner or a printer, or while the image data in the bit map memory is output to the printer. To realize these functions, at least one address generator is needed for transferring the image data between the image input/output device and the bit map memory. To store character fonts in the bit map memory and display them on the display, requires that at least two address generators be provided; one for generating the address, in order to write the character fonts into the bit map memory, and the other to read out the character fonts from the character fontment.
The conventional document processor is provided with one or two address generators for accessing the bit map memory. Therefore, it is impossible to perform concurrently the displaying of the character font and the transferring of the image data in the conventional document processor. Further, when the printer is printing a number of documents, the operator cannot execute another processing. In this respect, the operability of the conventional image processing apparatus is poor.